Work indexing mechanism for sewing machines



WORK INDEXING MECHANISM FOR SEWING MACHINES Filed Aug. 5, 1959 T. A. MGILL April 2, 1963 6 Sheets-Sheet 1 A ril 2, 1963 T. A. M GILL WORKINDEXING MECHANISM FOR SEWING MACHINES 6 Sheets-Sheet 2 Filed Aug. 5,1959 April 2, 1963 T. A. M GILL WORK INDEXING MECHANISM FOR SEWINGMACHINES Filed Aug. 5. 1959 6 Sheets-Sheet 5 A ril 2, 1963 T. A. mam.3,083,653

WORK INDEXING MECHANISM FOR SEWING MACHINES Filed Aug. 5, 1959 6Sheets$heet 4 Fig.7

April 2, 1963 1'. A. M GILL 3,083,653

WORK INDEXING MECHANISM FOR SEWING MACHINES Filed Aug. 5, 1959 6Sheets-Sheet 5 April 1963 T. A. MOGILL 3,083,653

WORK mozxmc MECHANISM FOR smwmc MACHINES Filed Aug. 5, 1959 6Sheets-Sheet 6 v JJCZA s I M/ a V EW NG C 23% INDEXING DRIVE JICZD MOTOR3 5 If Q Q 9 Q 1.40 I50 MAIN ON EMERGENCY 6 STOP 1: CIB CIA CIC DRIVE|60 '1' MOTOR 0N q Q ane" LOADER U wo :r mom 0N AL 4} L m \J me BUTTON@LoAoER me \JTAOTQR CYCLE m0 LASTART I W R30 IP-M V RZA H R48 msz S-l lBUTTON LOADER 28 NOHC J/AMS-I s-z ONE REV. CLUTCH NOHC r f; coummsCOUNTING R38 CLUTCH I CLUTCH Al V COIL FOOT/90 I swncu \f o.c. POWERSUPPLY cl i bn ||R4C H l is! M/ m. A 882%? i n I R4A A s-a cum? OPENER ms-4 CLAMP OPENER S-GII/CLOTH DEFLECTOR AIA s-s CONVEYOR STOP Fig.l0

United States Patent F 3,083,653 WQRK IINEEXING MECHANISM FGR SEWENGMACHINES Thomas A. McGill, Lunenburg, Mass, assignor, by mesneassignments, to The Singer Manufacturing Company,

Elizabeth, N.J., a corporation of New Jersey Filed Aug. 5, 1959, Ser.No. 831,894 4 Claims. (Ci. 1122) This invention relates to sewingmachines and, more particularly, to a sewing unit for producingautomatically a plurality of separate stitching operations on a garmentor other fabric article.

It is an object of this invention to provide a fabric manipulatingmechanism which may be loaded and unloaded with a minimum of attentionby an operator, and which will operate unattended.

It is also an object of this invention to provide a new and improvedwork indexing mechanism for shifting a work fabric between successivestitching operations.

Another object of this invention is to provide a novel unloading andstoring means for finished articles.

With the above and other objects and advantages in view as willhereinafter appear, this invention comprises the devices, combinations,and arrangements of parts hereinafter described and illustrated in theaccompanying drawings of a preferred embodiment in which:

FIG. 1 represents a front elevational View of a button sewing unithaving this invention applied thereto,

FIG. 2 represents a top plan view of the sewing unit of FIG. 1,

FIG. 3 represents a side elevational View of the Sewing unit of FIG. 1,

FIG. 4 is a cross-sectional view taken substantially along the line 44of FIG. 1, illustrating the microswitch control on the cam-shaft as wellas the work indexing cam thereon,

FIG. 5 is a cross-sectional view taken substantially along line 5-5 ofFIG. 1 illustrating the one revolution clutch and solenoid control forthe cam shaft,

FIG. 6 is an enlarged cross-sectional view taken substantially alongline 66 of FIG. 2 illustrating the work grippers of the indexing devicetogether with the gripper locating device and the gripper opener,

FIG. 7 is an enlarged cross-sectional view taken substantially alongline 7-7 of FIG. 2 illustrating the work pp FIG. 8 represents anenlarged front elevational view of a fragment of the sewing unit of FIG.1 illustrating the finished article holder and the sewing frame forcarrying a finished article over the holder,

FIG. 9 is an enlarged cross-sectional view taken substantially alongline 99 of FIG. 8, and

FIG. 10 is a circuit diagram of the sewing unit of this invention.

Referring particularly to FIGS. 1, 2 and 3, this invention isillustrated in preferred form as embodied in a sewing unit formanipulating a fabric panel relatively to a button sewing machine 11 ofa conventional type having an endwise reciprocable needle 12 defining astitching point, a starting lever 13 to initiate operation of the sewingmachine, a stop motion mechanism 14 to stop the machine after apredetermined number of stitches have been made, a button holding workclamp 15 of which the motion is controlled by a pattern cam '16, and awork clamp opening lever "17.

The sewing machine preferably operates in cooperation with a buttonloading device which may be of any form known in the art and preferablyis of the type having a control shaft 21 which is driven by a constantlyoperating button loader motor 22 and turns one revolu- Patented Apr. 2,1963 tion for each button loading operation but accomplishes thatrevolution in two separate increments. During the first increment ofturning movement, the control shaft 21 effects the movement of a buttoninserting arm 23 to load a button into the sewing machine work clamp,closes the sewing machine work clamp by way of a lever 24 connected tothe sewing machine Work clamp opening lever 17 by a pull rod 25, andactuates the sewing machine starting lever 13 by way of a lever 26connected to the sewing machine starting lever by a rod 27.

Upon completion of the sewing machine operation, the sewing machine stopmotion mechanism, in releasing the starting lever 13, releases the rod27 and the lever 25, which movement initiates the second increment ofturning of the control shaft 21 of the button loader. During the secondincrement of turning movement, the control shaft 21 shifts the buttoninserting arm 23 to pick up another button from the hopper feed chute28, opens the sewing machine work clamp by way of the lever 24 and thepull rod 25, and finally, shortly before completion of the revolution,pulses a microswitch MS- 1 for initiating operation of the work indexingmechanism. The button loading device 29 is preferably called intooperation by a solenoid 8-1 which triggers the button loading device bymeans of a pull rod 29.

The sewing machine ll and the button loading device 24) are supported ona cabinet 30 which together with an auxiliary supporting section 31 alsocarries the work indexing mechanism and the electric circuitry necessaryto effect automatic sequential operation of the sewing and work indexingoperation of this sewing unit.

Supported on pairs of sprocket wheels 32 carried on spaced horizontalshafts 33 and 34 disposed one at each side of the sewing machine are apair of endless link belts 35 providing an endless conveyor extendingtransversely across the front of the sewing machine 11 and havingvertically spaced substantially parallel horizontal limbs extendingbetween the pairs of sprocket wheels. The link belts 35 are stabilizedon guide rails 36 fastened on the cabinet 30 and supporting section 31and have secured thereon at spaced intervals pairs of work grippingclamps 37. As will be described hereinbelow, the conveyor is adapted tobe driven in only one direction and of each pair of work grippingclamps, one will be the leading clamp 37L and the other will be thetrailing clamp 37T as illustrated in FIG. 2. Preferably four pairs ofclamps are secured to the endless belts 35 and are secured on the beltswith equal spaces between pairs of clamps. Therefore, when a leadingclamp 37L is positioned adjacent to the stitching point on the upperlimb of the link belts in readiness to begin a cycle of operation of thesewing unit, that pair of clamps which is disposed on the under limb ofthe link belts will be disposed in substantially vertical alignmentbeneath the clamps on the upper limb.

The endless link belts 35 are driven from a drive shaft 40 journaled inthe cabinet 30 by Way of a link belt 41 interconnecting a sprocket wheel42 on the shaft 33 and a sprocket wheel 43 connected by means of gearingwith the drive shaft 40.

An electric motor 44, which is adapted to run continuously, is drivinglyconnected with the sewing machine by means of a belt 45 and is providedwith alternative driving connections with the drive shaft 40. A speedreducer 46 driven by a belt 47 from the motor 44 is operativelyconnected by link belts 48 and 49 to drive continuously a clutchsprocket wheel 50 on a cam shaft 51 journaled in the cabinet 30 and aclutch sprocket wheel 52 on the drive shaft 40.

The clutch sprocket wheel 59 on the cam shaft 51 is associated with aone revolution clutch 53 controlled by 3 a solenoid S-Z, actuation ofwhich serves to turn a cam 54- on the cam shaft 51 to oscillate a feedlever 55 having a follower 56 engaging the cam 54. A link 57 con' nectsthe feed lever with a rock arm 58 of a ratchet device 59. on the 'driveshaft 40 which imparts an increment of turning movement to the driveshaft 46 on the upstroke of the feed lever to index a work fabricbetween successive button sewing operations. A lug 6i! fast on the camshaft 51 engages a microswitch WIS-2 upon completion of the cam operatedwork indexing motionrto trigger the next sewing operation.

The clutch sprocket wheel 52 on the drive shaft 46 is associated with anelectric clutch 61 which is actuated, as will be described hereinbelow,to drive the work indexing mechanism to a starting position aftercompletion of the last sewing operation on each work fabric panel. 7Referring to FIGS.- 6 and 7, each work gripping clamp 37 includes a jaw70 fixed relatively to said endless link belt-s35 and formed with alengthwide slot 71 opening onto a hooked portion 72 at the outerextremity, which hooked portion is turned back upon the slotted portion.Pivoted in the slot 71 is a movable jaw member 73 formed with a serratedportion '74- disposed to engage the hooked portion 7 2 of the fixed jawto clamp work fabric inserted in the hooked portion. A spring 75 biasesthe serrated portion 74 into work clamping relation with the hookedportion 72 and each movable jaw is formed with an angularly extendinglimb '76 for shifting the jaws out of work clamping relation. 7

For opening the work gripping clamps a pair of levers 80 are provided,each fulcrumed on a vertical pin 81 in the link belt guide rail memberand disposed one on each side of the sewing machine, as illustrated inFIG. 2. The levers 80 are controlled by solenoids S3 and S-4. The levers80 are arranged, as illustrated in FIG. 6, each to engage the limbs 76of two work gripping clamps one carried on the upper limb of the endlessconveyor 35 and the other carried on the under limb thereof when theclamps occupy the starting position. As mentioned above, in the startingposition, alternate pairs of the work gripping clamps are disposed invertical alignment with each other, andthe starting position isaccurately defined by a conveyor stop solenoid S-S carried between theupper and under limbs of the endless link belt and having a stop lug 85carried on the armature thereof in the path of stop blocks 86 carried byscrews 87 on each leading. work gripping clamp 37L. When the leadingwork gripping clamps 37L traverse the upperlimb of the conveyor belts35, the stop blocks 86 have'two functions as illustrated in FIG. 6,i.e., one of engaging the stop lug 85 todetermine a starting position,and the second of underlying the guide rails 36 to hold the work clampsand link belts thereon. When solenoid S- is energized, the stop lug S5is drawn out of the path of the stop block 86 to release the indexingmechanism for each cycle of operation.

When the leading work gripping clamps 37L traverse the under limb of theconveyor belts 35, the stop blocks 86 perform an additional function ofactuating a microswitch MS-3, as illustrated in FIG. 2. The microswitchMS-3, as will be described in detail later, senses movement of the workgripping clamps into stopped position in response to which the cyclingcircuits of the sewing unit are dis abled. Microswitch MS-3 also sensesthe initial movement of the work gripping clamps out of stopped positionand acts to restore the conveyor stop 85 to effective stopping position.

The trailing work gripping clamps 37T are formed with blocks 88 havingthe sole purpose of retaining the trailing work gripping clamps on theguide rails. The blocks 87 a are formed with a clearance slot 89 toprevent engagement with the stop lug 85.

'The solenoids S-3 and S-4 for opening the work gripping clamps 37 arecontrolled by an operator influenced foot switch 96. The foot switch 90also serves to actuate a solenoid 5-6 simultaneously with actuation ofthe solenoids S-3 and S-4. The solenoid S-6 is operatively connectedwith a device which will now be described for handling fabric panelswhich are released from the work gripping clamps by the operation of thesolenoids S-3 and s 4 As illustrated in FIGS. 1, 2, 3 and 6, a smoothcover plate 1% overhangs the endless link belts 35 and covers aconsiderable portion of the fixed jaw '70 of the work gripping clamps37. When a work fabric panel is inserted in the work gripping clamps onthe upper limb of the endless conveyor 35, it is preferably draped overthe cover plate 1% and the panel slides along the cover plate until theclamps in which it is gripped traverse the sprocket 32. As the workgripping clamps are advanced along the under limb of the endlessconveyors 35, the fabric panel will depend substantially vertically fromthe inturned hooked extremities 72 of the work gripping clamps.

Referring to FIG. 3, a finished work holder in the form of an upstandingfolded sheet metal plate is secured on a bracket 111 carried on thefront of the cabinet 30. The work holder 11% is preferably disposedbeneath the Work gripping clamps 37 and outside of the vertical planesin which the finished work panels will depend from the inturned hookedextremities 72' of the work gripping clamps.

Pivoted in bearing lugs 112 secured beneath the bracket 111 is a workdeflecting frame 113 carrying at its upper extremity a rod 114 disposedto swing across the vertical plane in which the finished work panelswill depend from the work gripping clamps and to occupy a positionbetween the work gripping clamps and the top of the work holder 119. Thesolenoid S-6 is connected to the frame 113 beneath the bearing lugs 112by a tension spring 115. A stop arm "116 carried by the work deflectingframe 113 is fitted with a pad of cushioning material 117 and disposedto engage behind a portion of the auxiliary support 31 limiting theextreme position of the work engaging rod 114 outwardly beyond the workholder 110, as illustrated in dashed lines in FIG. 9. A cushion 118carried on the cabinet 30 determines the at-rest position of the workdefleeting frame 113, the frame preferably being balanced to return tothe at-rest position by gravity.

. 'When the foot switch 90 is depressed, therefore, and the workgripping clamps occupy the starting position, i.e., the position betweencycles of operation of the sewing unit as determined by the solenoidS-S, the solenoids S-3, S-4 and S-6 will be energized simultaneously toopen the work gripping clamps on the top of the conveyor to receive newwork, to open the work gripping clamps beneath the conveyor to releasethe finished work panel and simultaneously to swing the rod 114 of thework deflecting frame 113 across the work holder 110 to fold thefinished work panel across'the work holder.

When the work holding clamps are opened by the depression of the footswitch 90, new work may be located accurately in the clamps. by means ofadjustable edge guides 12% carried on the cabinet 30 and the auxiliarysupport 31. The edge guides 120 are preferably spring loaded upwardly soas to yield to permit the work gripping clamps to pass thereover. Anadjustable locating guide 121 secured to the cabinet is useful inestablishing proper button orientation with respect to the top or bottomedge of a garment panel.

A box 'carried at the rear of the auxiliary support 31 is provided forthe electrical components of the control circuit which need not bereadily accessible or physically related with the mechanism of thesewing unit. With reference to the circuit diagram of FIG. 10, thefollowing is a description of the preferred circuitry and the operationof the sewing unit of this invention.

In FIG. 10, the contactors are designated C, plain relays R, a countingcoil T, and a time delay relay A. The designation of each of thecontacts includes the desig- 5 nation of the relay or other device bywhich it is controlled, as for instance contacts CIA, ClB and 01C beingcontrolled by contactor C-l.

In the diagram, the source of electrical current is indicated as beingthree phase, supplying power directly to the drive motor 44 withcontacts C213, C2C and C2D, one in each of the three phase lines. Atransformer 140 provides low voltage single phase current for thecontrol circuits including a main power control circuit having anemergency stop switch 151 and a main power switch 155 for energizing acontactor C! to close contacts ClA holding in the switch 150, and toclose contacts ClB and C10 for supplying current to control busesbetween which the various control circuits are made.

The start and stop switches 160 and 161 for the sewing machine andindexing drive motor 44 are in series with a contactor C-Z between thecontrol buses, contacts CZB, CZC, and C2D in the three phase linessupplying the motor 44 being controlled by the contactor -2 as well asthe holding contacts C2A in parallel with the start switch 169.

The button loader motor 22 is in series between the control buses withcontacts RIB and RlC controlled by a relay R-l in series between thecontrol buses with start and stop switches 170 and 171. The start switch170 is in parallel with holding contacts R1A controlled by the relayR-l. The sewing unit is made ready for operation by closing the mainpower switch 156 and the drive and button loader motor switches 160 and170.

The foot switch 90 operates to actuate the clamp opening solenoids S3and 5-4 and the cloth deflector solenoid S6 by energizing a relay R-3closing contacts R3A in series with these solenoids between the controlbuses. Actuation of the relay R-3 also serves to open the normallyclosed contacts R3B in series with a clutch coil T-l of a countingclutch to reset the counting clutch each time the work gripping clampsare opened. The relay R3 also operates to open the normally closedcontacts R3C in series with the relay R-Z between the control buses. Therelay R-Z as will be described more fully hereinbelow is instrumental incontrolling the alternate sewing and indexing operations, and thecontacts RSC provide a safety interlock preventing either sewing orindexing operations from occuring while the work gripping clamps areopened.

When a work panel is properly located in the work gripping clamps andthe foot switch 9-0 is released to close the clamps, the operator caninitiate operation of the sewing unit by closing the cycle start switch18%. The switch 180, which is in series with a stop switch 181, thecontacts RSC, and the relay R-Z, energizes the relay R-Z which closesthe holding contacts in parallel with the cycle start switch 180 andcloses contacts R2B in series with microswitch MS-2 and the buttonloader release solenoid S-l. Since the microswitch MS2 is held closed bythe lug 6% between sewing cycles, closing of contacts RZB will releasethe button loader 20 which will operate as described earlier to load abutton in the sewing machine clamp, close the sewing machine clamp, andstart the sewing machine.

Operation of the sewing machine stop motion mechanism will signal thebutton loader to continued operation to pick up a new button, open thesewing machine work clamps, and momentarily close the microswitch MS-lshortly before the button loader device comes to rest.

As illustrated in the circuit diagram of FIG. 10, the microswitch MS-lis in series with the one revolution clutch releasing solenoid S-2 andalso with the counting coil T of the counting clutch.

Release of the one revolution clutch 53 causing one revolution of theindexing cam 54 will shift the work gripping clamps a distance equal tothe space desired between adjacent buttons, at the completion of whichthe microswitch MS-Z will be closed and held closed by the lug 60 on thecam shaft 51. The microswitch MS-2 signals a succeeding operation of thebutton loader so thit' by way of microswitches M34 and MS-Z, alternatesewing and indexing operations occur each indexing operation signalingone pulse to the counting coil T of the counting clutch.

Referring to the diagram of FIG. 10, the microswitch MS-3 which isoperated by the work gripping clamps 37L when the clamps occupy startingposition, comprises in etfect a pair of switches, one normally closedand the other normally open. The normally closed side of the microswitchMS-3 is in series with a relay R-4 and parallel contacts TlA controlledby the counting clutch T-l and R4A controlled by relay R-4 for holdingin the contacts TIA. When the counting clutch coil T-l is energized byvirtue of the counting coil T being pulsed a predetermined number oftimes, the contacts T1A will be closed and the relay R'4 energized. Thecontacts R4B in the holding in circuit in parallel with the cycle startswitch will be opened, thus breaking the circuit which energizes relayR-2. The alternate operation of the sewing machine and the indexingdevice will stop since the contacts RZB will break the circuit to thebutton loader release solenoid 8-1.

In order to drive the indexing device back to a new starting position,the DC. clutch 61 is energized by closing of the contacts R40 in theseries with the clutch in a DC. circuit from a DC. power supplyconnected between the buses. The clutch 61 will, therefore, drive theconveyor into starting position as determined by the conveyor stop 85.

Upon reaching starting position, microswitch MS3 will be engaged by theblock 86, the normally closed part will be held open deenergizing relayR-4, and the normally open part will be closed.

When the relay R-4 is deenergized, the contacts R4B in the cycle startholding circuit again close in readiness for a succeeding operation, theDC. clutch 61 is disengaged by the opening of the contacts R40 and theholding contacts RA are opened.

The normally open portion of microswitch MS-3 is not immediatelyefiective when held closed by the arrival of the parts into startingposition because of the open contacts RZC in series with that portion ofMS3 and with the time delay relay A-l. When the cycle start switch 189is again closed, however, the closing of contacts RZC completes acircuit energizing the relay A-l momentarily until the Work grippingclamps are given their initial movement to release the microswitchMS-ll. The contacts AlA in series with the conveyor stop solenoid S5will be closed to energize the solenoid 8-5 and withdraw the stopsuificiently long as to permit the indexing mechanism to partake of asucceeding cycle of work indexing movements.

Having set forth the nature of this invention, what is claimed hereinis:

1. In a sewing unit having a sewing machine, a work indexing means forshifting a fabric relatively to the stitching point of said sewingmachine comprising an endless conveyor supported for movement in onedirection relatively to the stitching point of said sewing machine,means constraining said endless conveyor in an elongate loop havingsubstantially straight and parallel elongate limbs, a plurality of pairsof work gripping clamps carried by said endless conveyor, the workgripping clamps of each of said pairs being carried in spaced relationalong said endless conveyor for engagement with opposite extremities ofa work fabric panel, each of said work gripping clamps comprising a pairof jaws, means supporting said jaws for movement relatively to eachother into and out of work gripping relation, means defining a startingposition of any of said plurality of pairs of Work gripping clampsrelatively to said sewing machine stitching point, said plurality ofpairs of work gripping clamps being spaced along said conveyor such thatin the starting position the leading work gripping clamp of a pair ofclamps on one of said conveyor links is disposed directly opposite thetrailing work gripping clamp of another pair of clamps on the oppositecon- 7 veyor limb; and a pair of work clamp opening solenoids carriedonsaid sewing unit, said solenoids being disposed for operative engagementin the starting position of said work gripping clamps to opensimultaneously both of a directly opposite set'of leading and trailingwork gripping clamps.

2. A sewing unit as set forth in claim 1 in which the endless conveyoris elongate horizontally and in which each of said pair of clamp openingsolenoids is effective in the starting position of the work grippingclamps to open a work gripping clamp on the upper limb of the conveyorfor loading of a work fabric panel, and a work gripping clamp on theunder limb of the conveyor for unloading a sewn work fabric panel.

3. In a sewing unit as set forth in claim 2, a means for storing a workfabric panel, after stitching has been completed comprising a fabricpanel supporting rail disposed beneath said under limb of the conveyorand at one side of the path of travel of a fabric panel depending fromsaid work gripping clamps in the under limb of said conveyor, a swingingframe pivoted on said sewing unit and including a fabric deflecting bardisposed between said work gripping clamps and said fabric supportingrail, and a solenoid means operative simultaneously with said work clampopening solenoids for swinging said frame to move said fabric deflectingbar across the path of travel of fabric panel depending from said workgripping clamps and across said fabric supporting rail to direct saidreleased fabric panel to a position draped over said fabric supportingrail.

, 4. In a sewing unit having a sewing machine, and a work-indexing meansfor shifting a work fabric panel relatively to the stitching point ofsaid sewing machine, including a workgripping clamp, means for unloadingand storing a work fabric panel after stitching has been completedcomprising, a work supporting member carried on said sewing unit at oneside of the path of travel of a fabric panel gripped in said workgripping clamp, andv References Citedin the file of this patent UNITEDSTATES PATENTS 1,243,679 Allen Oct. 23, 1917 1,709,788 Greene Apr. 16,1929 1,953,300 Holman Apr. 3, 1934 2,465,232 Jones et 'al. Mar. 22, 19492,674,965 Mclnerney et a1 Apr. 13, '1954 2,773,585 Caulfield Dec. 11,1956 2,899,919 Myska Aug. 18, 1959 2,908,378 Brown et al. Oct, 13, 1959

1. IN A SEWING UNIT HAVING A SEWING MACHINE, A WORK INDEXING MEANS FORSHIFTING A FABRIC RELATIVELY TO THE STITCHING POINT OF SAID SEWINGMACHINE COMPRISING AN ENDLESS CONVEYOR SUPPORTED FOR MOVEMENT IN ONEDIRECTION RELATIVELY TO THE STITCHING POINT OF SAID SEWING MACHINE,MEANS CONSTRAINING SAID ENDLESS CONVEYOR IN AN ELONGATE LOOP HAVINGSUBSTANTIALLY STRAIGHT AND PARALLEL ELONGATE LIMBS, A PLURALITY OF PAIRSOF WORK GRIPPING CLAMPS CARRIED BY SAID ENDLESS CONVEYOR, THE WORKGRIPPING CLAMPS OF EACH OF SAID PAIRS BEING CARRIED IN SPACED RELATIONALONG SAID ENDLESS CONVEYOR FOR ENGAGEMENT WITH OPPOSITE EXTREMITIES OFA WORK FABRIC PANEL, EACH OF SAID WORK GRIPPING CLAMPS COMPRISING A PAIROF JAWS, MEANS SUPPORTING SAID JAWS FOR MOVEMENT RELATIVELY TO EACHOTHER INTO AND OUT OF WORK GRIPPING RELATION, MEANS DEFINING A STARTINGPOSITION OF ANY OF SAID PLURALITY OF PAIRS OF WORK GRIPPING CLAMPSRELATIVELY TO SAID SEWING MACHINE STITCHING POINT, SAID PLURALITY OFPAIRS OF WORK GRIPPING CLAMPS BEING SPACED ALONG SAID CONVEYOR SUCH THATIN THE STARTING POSITION THE LEADING WORK GRIPPING CLAMP OF A PAIR OFCLAMPS ON ONE OF SAID CONVEYOR LINKS IS DISPOSED DIRECTLY OPPOSITE THETRAILING WORK GRIPPING CLAMP OF ANOTHER PAIR OF CLAMPS ON THE OPPOSITECONVEYOR LIMB, AND A PAIR OF WORK CLAMP OPENING SOLENOIDS CARRIED ONSAID SEWING UNIT, SAID SOLENOIDS BEING DISPOSED FOR OPERATIVE ENGAGEMENTIN THE STARTING POSITION OF SAID WORK GRIPPING CLAMPS TO OPENSIMULTANEOUSLY BOTH OF A DIRECTLY OPPOSITE SET OF LEADING AND TRAILINGWORK GRIPPING CLAMPS.